Portable fluid storage tanks used to store well fracturing fluids are well known in the art. Such tanks are available in two general types: trailer tanks and skidded tanks. Trailer tanks are horizontal tanks shaped much like a semi-truck trailer and have at least one rear axle with wheels. Trailer tanks generally have a capacity of about 350-500 barrels. They are towed by a trailer tractor to a well site and parked in side-by-side and back-to-back double rows. A frac manifold must be installed between each pair of double rows to pump fluid from the tanks. Skidded tanks are cylindrical tanks with skids welded to a side surface. The skidded tanks generally have a capacity of about 200-500 barrels. The skidded tanks are transported to a well site on specially designed trucks or trailers, where they are offloaded and normally tipped to an upright position using cables or chains pulled by winches or a suitable vehicle.
Each type of tank has its advantages and disadvantages. Trailer tanks have a low profile but occupy a large area per barrel of fluid capacity. Skidded tanks, once tipped upright, occupy less area per barrel of fluid capacity, but they require much more handling, space for the tipping operation, and they cannot be as closely packed because of the tipping operation.
Fracturing a gas well in a shale formation, for example, often requires a very large volume of fracturing fluid. Since it is only economical to fracture the well in a single uninterrupted procedure due to equipment rental and labor costs, all of the required fracturing fluid must be stored at the well site before the fracturing operation begins. If a large frac is to be performed, an appropriately sized area around the well must be prepared for the frac tanks and other equipment required to perform the fracturing operation. The required area must be acquired or leased, graded and, if necessary, covered with an appropriate surface aggregate. All of this is time-consuming, expensive and environmentally undesirable. It is therefore desirable to keep the well site as small as possible. In order to facilitate this, space-efficient fluid storage is advantageous.
There therefore exists a need for a portable fluid storage tank that provides space-efficient fluid storage.